Recovery of color developing agents



United States Patent 3,502,577 RECOVERY OF COLOR DEVELOPING AGENTS Bernard A. Hutchins, Livonia, and Robert S. Walsh,

Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey N0 Drawing. Filed Mar. 27, 1968, Ser. No. 716,367 Int. Cl. C02c 5/02 US. Cl. 210-59 14 Claims ABSTRACT OF THE DISCLOSURE Potential water pollutants including primary aromatic amine color developing agents are recovered, alone, or simultaneously with color-forming couplers or benzyl alcohol from developer solutions in a separable, second phase by admixture with a water-soluble salt under limited pH conditions.

This invention relates to color photography and to the recovery of color developer solution components. More particularly, this invention relates to the recovery of potential water pollutants including color developing agents that are suitable for use in photographic color development processes.

Large quantities of color developing solutions are used in the processing of exposed photographic elements in order to produce color photographs. It is the color developing solutions that produce the dye images that form the color picture in the processed element. In the processing of color subtractive-type photographic elements, the final picture is usually made by the formation of a cyan dye image, a yellow dye image and a magenta dye image in superposed relationship.

The magenta dye image development, for example, is accomplished with an alkaline developer solution which contains a primary aromatic amine color developing agent, such as N(Z-amino-S-diethylaminophenethyl)methane sulfonamide hydrochloride, and a magenta-forming coupler which is usually a 2-pyrazolin-5-one or a coumarone type coupler. Where exposed silver halide in the magenta image layer is developed to silver, color developing agent is oxidized to a compound that couples with the magenta-forming coupler present to form a nondifiusing dye image. The cyan and yellow dye images are formed in a similar manner with cyan dye-forming and yellow dye-forming couplers, respectively.

In commercial color processing of color film, a continuous flow of color film is conducted through various processing solutions including the color developers in a processing machine. The concentrations of the components of the developer solutions must be maintained within certain specified ranges in order to give good sensitometric results. Thus, it is usual practice to replenish the various developer solutions by a controlled flow of the appropriate replenisher solution at the necessary rate. The flow of color developer replenisher into a processing machine color development tank, for example, displaces used color developer solution which still contains substantial amounts of color developing agent, color-forming coupler and other such materials which are relatively expensive to replace. Not only is it undesirable to lose these materials, but it is highly undesirable to sewer such solutions, since some of them contain materials such as benzyl alcohol in addition to the developing agents which have a substantial biochemical oxygen demand and an adverse effect on fish and wildlife that eventually come into contact with the waters into which these materials are deposited.

7 It has been proposed to recover the various components of the color developing solution for reuse by means of certain techniques including solvent extraction, evaporative or freezing-out procedures, ion exchange and the like. However, none of these processes has been completely satisfactory for commercial purposes. Certain of the proposed processes are complicated and difiicult to operate. Furthermore, while some of the proposed processes permit the recovery of certain of the components of the color developing solution, e.g., the color-forming coupler, the color developing agent and benzyl alcohol (when used in the developer) still remain in solution and must be discarded.

It is therefore an object of the present invention to provide a novel process for the recovery of color developing agents from color developer solutions.

Another object of the invention is to provide a novel process for the recovery of color developing agents from solution which is relatively simple and easy to operate.

Still another object of the invention is to provide a novel process for the recovery of certain color-forming couplers or benzyl alcohol, as well as color developing agents, which process prevents the pollution of streams and lakes with these materials which have biochemical oxygen demand.

These and other objects are accomplished according to the process of the present invention, which process comprises admixing a color developer solution having a pH in the range of between about 9 and about 14 with a water soluble salt with the solution in an amount sufficient to .result in the formation of a developing agent containing second phase that is separable from the main body of color developer solution phase. The newly-formed second phase can be either in the form of a liquid or a solid phase depending upon the materials being recovered. The developing agent phase is easily recovered or separated from the main body of developer solution by any suitable means including filtration, centrifuging, decanting, and the like, thus substantially reducing the biochemical oxygen demand of the main body of the developer solution which is then discarded. The recovered developing agent or developing agent with color-forming coupler or developing agent with benzyl alcohol is then advantangeously used to make fresh color developer solution for processing.

According to one aspect of the invention, the color developing agent is recovered from the color developer solution.

According to a second aspect of the invention, both the color developing agent and a color-forming coupler are simultaneously recovered from the color developer solution.

According to still another aspect of the invention, the color developing agent and benzyl alcohol are simul taneously recovered from the color developing solution.

The process of the present invention is applicable to the recovery of color developing agents from color developing solutions, usually used or spent color developer solutions, and provides recovered color developing agents of suflicient purity that they are advantageously reused in commercial color developing processes. For purposes of illustration, the process will hereinafter be discussed as relating to the recovery of developing agents from used 3 developer solutions, however, the process is also advantageously used to recover color developing agent from fresh color developer solutions that have not been used for color processing.

According to one aspect of the invention, the used color developer solution is first treated for the removal of an aqueous-alkaline-solution-soluble, diflusible dye-forming coupler. This may be done by any suitable means including acidification of the solution with a mineral acid. However, it is preferred to pass the used color developer solution to a precipitation tank into which sufiicient carbon dioxide gas is introduced through a distribution system or sparger to lower the pH of the solution to the level at which the coupler will precipitate. At this point the coupler is converted to the free acid form of the coupler. The precipitate coupler is filtered or centrifuged off and the efiluent is treated for the recovery of the developing agent.

The pH of the effluent is adjusted to a value in the range of between about 9 and about 14, preferably between about 10 and about 11. It is vital to the success of the process of the present invention that the pH be controlled within this pH range. Otherwise, the desired recovery of the color developing agent cannot be accomplished. The desired pH level may be provided in any suitable manner. Preferably, a soluble hydroxide is employed. Especially preferred basic materials include, for example, the alkali metal hydroxides, such as sodium and potassium hydroxide and the like.

Next, the coupler-tree developer solution having a pH in the range of between 9 and 14 is admixed with a water-soluble salt in amounts suificient to result in the formation of a separable, developing agent-rich phase.

Suitable water-soluble salts for the purposes of the present invention include, for example, the inorganic salts having a solubility of at least 30 grams per liter, particularly the alkali metals, e.g., sodium, potassium, etc., and ammonium salts. Typical anions include sulfate, bisulfate, sulfite, carbonate, bicarbonate, chloride, and the like. Thus, exemplary water-soluble Salts include sodium sulfate, sodium bisulfate, potassium sulfate, potassium bisulfate, sodium chloride, potassium carbonate, ammonium chloride, ammonium sulfate, etc. A preferred water-soluble salt is sodium sulfate.

The water-soluble salt is admixed with the developer solution in amounts sufficient to cause the formation of a separate and distinct phase that is rich in the developing agent and is easily separable from the salt solution phase which retains substantially no developing agent. Usually, to cause the desired phase separation, it is advantageous to add enough water-soluble salt to bring the salt content of the used developer solution to a total concentration in the range from about 60 to about 500 grams per liter of solution, preferably between about 125 and about 250 grams per liter.

The temperature which may be employed for the admixture of the water-soluble salt and the used developer solution may be varied over a wide range. For example, the temperature may be in the range of between about 40 F. and about 150 5., preferably in the range of between about 65 F. and about 85 F. Room temperatures are especially preferred from the standpoint of economy and ease of operation. The higher temperatures require the use of more water-soluble salt than do the lower temperatures in order to cause the formation of the easily separable developing agent-rich phase. Any temperature may be employed, so long as a separate phase is formed. The salt is admixed with the developer until the desired amount of salt is dissolved.

The addition of the water-soluble salt to the used developer solution may be conducted in any suitable manner. Thus, the salt may be admixed with the developer solution in a batchwise or continuous manner. However. it s preferred to conduct the entire process in a continuous manner with the salt being added to an agitated tank by a suitable feeding means, such as a screw feeder. The developing agent-rich phase is continuously withdrawn from the phase that is now depleted of developing agent by a suitable separatory means, such as a centrifuge. It is preferred to employ suitable automatic control means for the continuous automatic handling of the materials involved. The use of programmed devices including automatic flow control, liquid level control, pressure responsive, temperature responsive, and pH measurement means and the like, are well known to those skilled in the art and may be suitably employed.

Commercial color processing is usually done on a continuous basis. Accordingly, the present invention contemplates the continuous passage of used color developer solution to a suitable tank or vessel where the pH of the spent solution is measured. Next, mineral acids are metered to the tank or carbon dioxide is bubbled through the tank in order to lower the pH of the solution and precipitate the coupler. The pH of the efliuent is then measured and adjusted to a value within the range of between 9 and about 14 by the addition of a suitable base, i.e., sodium hydroxide, if necessary, in a separate vessel. The water-soluble salt is then automatically and continuously added to the solution in the manner previously described.

The color developing agents that may be recovered according to the process of the present invention are the primary aromatic amine silver halide and color developing agents, such as the p-phenylenediamines including alkyl phenylenediamines and alkyl toluenediamines which in the oxidized form couple with photographic dye-forming couplers to produce photographic image dyes. Typical examples of p-phenylenediamine developers are the N-alkyl sulfonamido alkyl-p-phenylenediamines of U.S. Patent 2,193,015, the sulfonamido substituted p-phenylenediamines of U.S. Patent 2,548,574, the substituted pphenylenediamines of U.S. Patent 2,552,240, 2,552,242, 2,566,271, etc. All of these developing agents have an unsubstituted amino group which enables the oxidation product of the developer to couple with the color-forming products that form a dye image. The primary aromatic amine color developing agents used to advantage in our process include those having the following formula:

wherein R represents hydrogen, an alkyl group having from 1 to 6 carbon atoms, e.g., methyl, ethyl, propyl, butyl, hexyl, etc., in which the alkyl group is unsubstituted or substituted with groups such as hydroxy, amino, acetamido, methylsulfonamido, e.g., B-hydroxyethyl, aminoethyl, acetamidoethyl, methylsulfonamidomethyl, methylsulfonamidoethyl, etc., an alkoxy group having from 1 to 6 carbon atoms, e.g., methoxy, ethoxy, hexoxy, etc., hydroxy, halogen, e.g., chloro, bromo, iodo, fluoro, etc.; R represents any of the groups represented by R; R represents an alkyl group, e.g., methyl, ethyl, fi-hydroxyethyl, ,B-aminoethyl, propyl, butyl, etc.; and R represents an alkyl group, e.g., methyl, ethyl, p-hydroxyethyl, p-aminoethyl, fl-methylsulfonamidoethyl, {it-methylsulfonamidomethyl, lit-acetamidoethyl, ,B-ehtoxyethyl, etc. In-

cluded among the color developing agents are such typical illustrative examples as 2-amino-5-diethylaminotoluene hydrochloride, 4-amino-N-ethyl-N-(,B-rnethanesulfonamidoethyl)-m-toluidine sesquisulfate monohydrate, N-(2- amino-5-diethylaminophenethyl)methane sulfonarnide, 4- amino-N-ethyl-N-(/S-hydroxyethyl)-3-methyl aniline sulfate, N,N-diethyl-p-phenylenediarnine hydrochloride, etc. Additional examples of such color developing agents are found on pages 294 and 295 of Mees et al., Theory of the Photographic Process, third edition; the disclosure of which is hereby incorporated by reference.

As previously mentioned, another aspect of the invention involves the simultaneous recovery of the colorforming coupler and color developing agent. According to this aspect of the invention, the used color developing solution is not pretreated for the removal of the coupler, but rather, the pH of the spent developer is adjusted, if

necessary, to within the range of between 9 and about 10.5, by the addition of a suitable acidic material, e.g., sulfuric acid. Next, the water-soluble salt, e.g., sodium sulfate is added, as before, to cause the formation of a second phase, which is in the form of a precipitate, that is rich in developing agent and color-forming coupler. The temperatures and concentrations previously employed are suitable for usage in this embodiment of the invention.

The resulting developing agent and coupler-rich phase is filtered or centrifuged oil of the remaining liquid phase. The recovered material may then be dried and stored for later use or may be immediately admixed with suitable developer solution constituents, e.g., hexylene glycol, sodium hydroxide, etc., so as to prepare a new color developer solution which may then be employed in color processing operations without further purification.

Typical color developer solutions that are used in color processing which have the color-forming coupler in the developer solution comprise the compositions shown in Table 1 below:

TABLE 1 Concentration range Ingredient: (grams per liter) Color developing agent 0.5-6.0 Alkali metal sulfite 0.5-250 Coupler 0.56.0

The simultaneous recovery of the color developing agent free base and the color-forming coupler has the advantage that separate recovery operations and equipment are not required for the individual recovery of the developing agent and coupler, respectively, as in the mode of the present invention previously discussed.

The aqueous-alkaline-solution soluble, color-forming couplers that can be simultaneously recovered that the developing agents according to the present invention include the cyan-dye forming couplers, the yellow-dye forming couplers and the magenta-dye forming couplers. Typical cyan couplers are the phenolic and the naphtholic type couplers such as the nitro-naphthol couplers of Vittum et al. U.S. 2,266,452, issued Dec. 21, 1941; the naphtholic couplers of Porter et al. U.S. 2,295,009, issued Sept. 8, 1942; the substituted naphthamide couplers of Salminen et al. U.S. 2,313,586, issued Mar. 9, 1942; the phenolic couplers of Vittum et al. U.S. 2,338,- 676, issued Jan. 4, 1944; the phenolic and naphtholic couplers containing sulfonamide groups of Schinzel U.S. 2,356,475, issued Aug. 22, 1944; of Vittum et al. U.S. 2,362,598, issued November 14, 1944; the acylamino phenol couplers of Vittum et al. U.S. 2,369,929, issued Feb. 20, 1945; the heterocyclic group substituted phenols and naphthols of Salminen et al. U.S. 2,976,146, issued Mar. 21, 1961; the coupler 2-(o-acetamido-B-phenylethyl)-l-hydroxyuaphthamide of Vittum et al. U.S. 3,002,836, issued Oct. 3, 1961, etc.

Included among the yellow-dye forming couplers are those such as the acetoacetamides and cyanoacetamides of Mannes et al. U.S. 2,108,602, issued Feb. 15, 1938; the acetoacetanilides of Mannes et al. U.S. 2,113,330, issued Apr. 5, 1938; the diketone couplers of Vittum et al. U.S. 2,206,142, issued July 2, 1940; the sulfonamide substituted yellow couplers of Vittum et al. U.S. 2,271,238, issued Jan. 27, 1942, and Vittum et al. U.S. 2,364,675, issued Dec. 12, 1944; the sulfonic ester couplers of Porter et al. U.S. 2,289,805, issued July 14, 1942; the cyanoacetyl couplers of Allen et al. U.S. 2,313,498, issued Mar. 9, 1943; the carboxylic acid amide couplers of Salminen et al. U.S. 2,359,332, issued Oct. 3, 1944; the benzoyl acetanilide couplers of Weissberger et al., U.S. 2,407,210, issued Sept. 3, 1946; the N-(benzoylacetyl)-benzamide type couplers of Weissberger et al. U.S. 2,439,352, issued Apr. 6, 1948.

Typical magenta-dye forming couplers are those such as the 3-substituted 2-pyrazolin-5-oues of Porter et al. Re. 22,329 (of U.S. 2,311,082), reissued June 1, 1943; the iminopyrazolone couplers of Porter et al. U.S. 2,311,- 081, issued Feb. 16, 1943; the 1,3-substituted 2-pyrazolin- 5-one couplers of Porter et al. U.S. 2,343,703, issued Mar. 7, 1944; the sulfonamide substituted 2-pyrazolin-5- one couplers of Vittum et al. U.S. 2,353,205, issued July 11, 1944; the developer solution incorporated acylated amino 2-pyrazolin-5-one couplers of Porter et al. U.S. 2,369,489, issued Feb. 13, 1945, the developer solution incorporated 1 cyanophenyl 3-acylamino-Z-pyrazolin-S- one couplers of Weissberger et al. U.S. 2,511,231, issued June 13, 1950.

According to still another aspect of the present invention, used developer solutions may be treated to effect the simultaneous recovery of the developing agent and benzyl alcohol. As noted above, the recovery of benzyl alcohol as well as the developing agent is especially desirable from the standpoint of reducing water pollution by materials having a biochemical oxygen demand, and of economic considerations.

According to this embodiment of the invention, the pH of the color developer solution that contains the developing agent and the benzyl alcohol is adjusted, if necessary, to a value in the range of 9 and about 11, preferably to a pH of about 10. As in the previous embodiments, the water-soluble salt is added to solution in sutficient quantity to result in the formation of an easily separable second phase which is rich in developing agent free base and benzyl alcohol. The temperatures and concentrations previously described for admixing the Water-soluble salt may be employed herein.

The recovered phase is then either stored as is or is mixed with additional ingredients to form a new color developer solution. Typical solutions containing the benzyl alcohol are the color developer solutions which are used in the processing of color photographic films and papers that contain incorporated color-forming couplers. Typical developer solutions of this type comprise the compositions shown in Table 2 below:

TABLE 2 Concentration range Ingredient: (per liter) Color developing agent g 20 14.0 Benzyl alcohol ml 215.0 Alkali metal sulfite g 0.525.0

As in the case of the simultaneous recovery of the developing agent and coupler, the concurrent recovery of the color developing agent and benzyl alcohol is highly desirable from the standpoint of economy and simplicity of operation.

The following examples are included for a further understanding of our invention.

Example 1 Used magenta developing solution machine overflow containing the developing agent N(2-amino-5 -diethylaminophenethfyhmethane sulfonamide hydrochloride, and the magenta dye-forming coupler, 3-(2,4 dichloroanilino)- l-(2,4,6-trichiorophenyl)-2-pyrazolin-5-one is passed to a storage tank. The magenta developer solution contains the following ingredientswhen freshly prepared:

TABLE 3 if Ingredient: Concentration Sodium tetraphosphate g 5.0 Na SO i g 8.0 KI(0.1%) Z ml 25.0 NaBr g 1.0 N32S04 g NaOH g 3.85 Color developer g 2.0 Coupling agent e g 1.5 Hexylene glycol ml 10.0 1-phenyl-3-pyrazolidone g .06

Water to make 1.0 liter. pH at 80 F.: 12.10.

1 N-(2-amino-5-diethylamlnophenethyl) methane sulfonamide hydrochloride.

3 (2,4-dicnloroanilino)-1-(2,4,6-trichlorophenyl)-2-pyraz Olin-done.

The used solution is treated in the storage tank by bubbling carbon dioxide gas through a sparger at the bottom of the tank until the pH of the developer solution reaches approximately 8. The coupler precipitates from the solution and is separated from the solution by means of a centrifuge. The precipitate is washed and dried and is used to make a fresh magenta developer solution. Meanwhile, the centrifuge eiiiuent is admixed with sodium hydroxide in order to raise the pH to approximately 10. The resulting solution is then admixed with 200 grams of sodium sulfate per liter of solution in a stirred tank at room temperature until a second phase forrns at the top of the vessel. This second phase, which appears oily in nature, is filtered ofi of the spent developer solution and is dried in air. Analysis of the resulting material indicates that it is essentially the developing agent free base, N-(Z-amino 5 diethylaminophenethyl)methane sulfonamide. A yield of about 79 percent is realized. Samples of color photographic film are image exposed. One set of the exposed samples are developed in a process which uses fresh magenta developer solution made from the recovered developing agent and another set are developed in the same process using a fresh magenta developer solution which contains fresh developing agent. Both of the magenta developer solutions contain the ingredients indicated in Table 3 supra. The process using recovered developing agent produces color pictures of good quality, comparable to the quality produced by the non-recovered or fresh developing agent.

Example 2 The procedure of the previous example is repeated with the exception that 200 grams of sodium sulfate per liter of solution are dissolved in the centrifuge efiluent prior to adjusting the pH of the solution to approximateiy by means of sodium hydroxide addition instead of afterwards. The results obtained are identical to those realized in Example 1 and a good yield of high quality developing agent free base is covered. Processing of exposed color film with a magenta developer solution containing the recovered developing agent produces color pictures having quality comparable to that obtained with fresh developing agent.

Example 3 The procedure of Example 1 is conducted employing a use-:1 cyan developer solution having essentialiy the following composition when freshly prepared:

Water to make 1.0 liter. pH at F.: 12.30.

4 amino 3 methyl-N-ethyl-N-(fi-hydroxyethyl)anllino -ulfate. b 2 N- (o-acetamidophenethyl) -1-hydroxy-2-naphthamide. A high purity, concentrated developing agent free base is recovered. The recovered developing agent is advantageously used to make fresh cyan developer solution for processing image exposed color film.

Example 4 The procedure of Example 1 is repeated, except that a used yellow developing solution is treated for recovery of the developing agent free base. The yellow developer, as a fresh mixture, contains the following ingredients as set forth in Table 5 below:

TABLE 5 Ingredient: Concentration Sodium tetraphosphate g 5.0 Na so g 10.0 NaBr g 2.30 KI (0.1%) ml 32.0 Polyethylene oxide, m. wt. 4000 g 1.0 NaOI-I g 2.22 Na SO g 60.0 l-phenyl-3-pyrazolidone g 0.25 Developing agent g 2.00 Coupling agent g 2.20

"Water to make 1.0 liter. pH at 80 F.: 12.20.

1 N,N-diethyi-p-phenylenediamine monohydrochloride. 3 Benzoyl-o-methoxy acetanilide. The developing agent free base recovered in this example is advantageously used to prepare fresh yellow color de veloper for processing image exposed color photographic materials.

Examples 5-9 The procedure of Example 1 is repeated employing one liter portions of the used magenta developing solution of Table 1 with various water=soluble salts at concentrations shown in Table 6 below:

TABLE 6 Example Concentration No. Water-soluble salt (grams/liter) 5 Sodium bisulfite 220 6. Potassium sulfate- 60 7. Potassium biearbonat 8. Ammonium chloride. 200 9 Ammonium sulfate 200 The color developer free base recovered by these examples is advantageously used to prepare fresh magenta developer solution for processing color photographic film.

The following examples are illustrative of an aspect of the present invention in which the developing agent free base and the color forming coupler are simultaneously recovered. The advantage of this mode of operation is, of course, that additional operations and equipment are not required for the individual recovery of the colorforming coupler and the developing agent.

9 Example Used magenta developer solution having the freshly mixed composition shown in Table 3 above is adjusted to a pH of 9.0 by the addition of H 50 Two hundred grams of sodium sulfate are added to the solution With stirring until the salt is dissolved. A second phase in the form of a precipitate comprising the developing agent free base and color-forming coupler is formed. A portion of the precipitate is then air dried and stored for later usage, while the remainder is immediately redissolved in a solution of hexylene glycol and sodium hydroxide and is suitable for use as a magenta developer solution after appropriate amounts of additional developing agent and coupler are added. The color processing results achieved with the regenerated solution are photographically indistinguishable from fresh coupling agent and developing agent.

The following examples illustrate still another aspect of the invention. According to this embodiment, color developing solutions that contain benzyl alcohol are treated for the simultaneous recovery of the benzyl alcohol and developing agent free base.

Example 11 A solution comprising the ingredients set forth in Table 7 below is provided having a pH between 9.0 and l 1.0.

TABLE 7 Ingredient: Concentration Benzyl alcohol ml 12.0 Color developing agent 1 g 8.0 Sodium tetraphosphate g 2.0 N21280:; g Na CO (anhydrous) g 22.0 NaHCO g 2.8 NaBr g 0.4 NaCl g 0.6 Hydroxylamine sulfate g 4.0

Water to make 1.0 liter.

4 amino-N-ethyl-N(IS-methane sulfonamidoethyl)-m-toluidine sesquisulfate. Next, 250 grams of sodium sulfate are admixed with each liter of the developer solution for a period of at least 30 minutes. A second phase appears in the form of a floating, oily, liquid layer of benzyl alcohol and the color developing agent. This liquid layer is separated from the remaining liquid phase that is now depleted of benzyl alcohol and the color developing agent. The recovered layer is admixed with the remaining constituents of the developer solution of Table 7, i.e., all those except the benzyl alcohol and the color developing agent, and is suitable for reuse in color processing of photographic elements containing incorporated couplers.

Example 12 The pH of a used developer solution having a composition comprising the ingredients shown in Table 8 below is adjusted to a value of 10.

TABLE 8 Ingredient: Concentration Benzyl alcohol rnl 4.5 Sodium tetraphosphate g 5.0 Na SO .g 7.5 Na PO -l2H O g 36.0 NaBr g 0.3 KI (0.1%) -ml 24.0 NaOH ..g 3.85 Color developing agent g 11.0

Water to make 1.0 liter.

1 4 amino N ethyl NUS-methane sulfonamidoethyD-mtoluidine sesquisulfate. Sodium sulfate is added to the foregoing solution in the amount of 250 grams per liter in order to form an oily, second phase which upon analysis is found to comprise 10 benzyl alcohol and the color developing agent free base.

Utilization of the recovered material in a developer solution results in color pictures of excellent quality.

1 4 amino-N-ethyl-N( S-methane sulfonamidoethyl) -mt0luidine sesquisulfate. The resultant oily phase is recovered and admixed with the ingredients shown in Table 9, except for the benzyl alcohol and the developing agent. This solution is employed as a color developer solution for photographic elements containing incorporated color-forming couplers and produces color pictures of good quality comparable to those produced with freshly-produced developer solutions.

Example 14 Two hundred grams of sodium sulfate are added to each liter of a used developing solution that contains the ingredients set forth in Table 10 below:

TABLE 10 Ingredient: Concentration Benzyl alcohol ml 5 .0 Na SO ..g NaBr g 1.40 KI mg 0.5 NaOH g 12.5 N32B407'5H2O g Developing agent g 6.0 Water to make 1.0 liter.

1 4 amino N ethyl N(B-methaue sulfonamidoethy1)-mtoluidine sesquisulfate. At the end of about 30 minutes of agitation, a second, oily phase containing the benzyl alcohol and the developing agent free base appears as an upper layer and is separated by draining the lower layer from a separatory tank. This remaining liquid phase is now admixed with the materials shown in Table 10 except for the benzyl alcohol and developing agent to prepare a color developing solution that is used advantageously in color processing of photographic materials.

Examples 15-16 The procedure of Example 14 is repeated employing the water-soluble salts in concentrations shown in Table 11 below:

TABLE 11 Example Concentration N 0. Waters0luble salt; (grams/liter) 15 Potassium sulfite 16 Potassium carbonate The benzyl alcohol and color developing agent phase is recovered in each case and advantageously admixed with the remaining ingredients of Table 10 to prepare a color developer solution for color processing.

- Example 17 Used color developer solution having 2-amino-5-diethylaminotoluene as the color developing agent is collected from the overflow from the color developing tank of a processing machine. Five hundred grams of sodium sulfate per liter of solution are added to the used developer solution and mixed until dissolved. The Z-amino-S-diethylaminotoluene that separates from the solution as an oily second phase is removed and used advantageously to prepare fresh color developer solution for use in the color process.

The process of the present invention provides a simple and effective means of recovering primary aromatic amine color developing agents, couplers and benzyl alcohol from developer solutions, which materials are advantageously reused in color processing operations. Furthermore, it provides a substantial contribution to water pollution abatement by substantially reducing the biochemical oxygen demand in the waste water while at the same time eliminating the wasteful disposal of costly developer solution components.

The term separable second phase as employed herein is defined as a separate and distinct phase, either solid or liquid, that is susceptable of being separated by ordinary physical methods, e.g., filtration, centrifugation and the like.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it Will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A method for lowering the biochemical oxygen demand of waste water from photographic color processing by the recovery of water pollutant material comprising a primary aromatic amine color developing agent, said method comprising admixing photographic developer processing solution containing a primary aromatic amine color developing agent and having a pH in the range of between about 9 and about 14 with a water-soluble salt in at least an amount sufficient to form a separable second phase containing said developing agent, and separating said second phase from the resulting admixture.

2. The method of claim 1 wherein the water-soluble salt is employed in an amount in the range from about 60 to about 500 grams per liter of developer solution.

3. A process for lowering the biochemical oxygen demand of waste water from a color processing machine by recovery of water pollutant material comprising a primary aromatic amine color developing agent having the formula:

wherein R and R each represents a member selected from the class consisting of hydrogen, an alkyl group having from 1 to 6 carbon atoms, an alkoxy group, a hydroxy group, and a halogen atom; R represents an al-kyl group; and R represents an alkyl group, said process comprising the steps: (1) providing a developer solution containing a primary aromatic amine color developing agent and having a pH in the range from about 9 to about 14, (2) admixing a water-soluble salt selected from the class consisting of an alkali metal salt and an ammonium salt in an amount in the range from about to about 500 grams per liter of the said developer solution that is sufiicient to form a separable second phase containing said developing agent, and (3) separating said second phase from the resulting admixture.

4. The process of claim 3 wherein the water-soluble salt is an alkali metal salt.

5. The process of claim 3 wherein the water-soluble salt is sodium sulfate.

6. The process of claim 3 wherein the developer solution additionally contains an aqueous-alkaline-solutionsoluble, diifusible dye-forming coupler, and the pH of the developer solution is between about 9 and about 10.5.

7. The process of claim 3 wherein the developer solution additionally contains benzyl alcohol, and the pH of the developer solution is between about 9 and about 11.

8. The process of claim 1 wherein the developer solution additionally contains a color-forming coupler that is recovered prior to adjusting the pH to a value in the range between about 9 and about 14.

9. The process of claim 3 wherein the developing agent is N(Z-amino-S-diethylaminophenethyl)methane sulfonamide.

10. The process of claim 3 wherein the developing agent is 4 amino N ethyl N (B methanesulfonamidoethyl)-m-toluidine.

11. The process of claim 6 wherein the coupler is 3(2,4- dichloroanilido) l (2,4,6 trichlorophenyl) 2 pyrazolin-S-one.

12. The process of claim 3 wherein the developing agent is N,N-diethyl-p-phenylenediamine.

13. The process of claim 3 wherein the developing agent is 2-amino-5-diethylaminotoluene.

14. The process of claim' 3 wherein the developing agent is 4-amino-N-ethyl-N-(fi-hydroxyethyl)-3-methylaniline.

References Cited UNITED STATES PATENTS 3,201,412 8/1965 Anselm 88l X MICHAEL E. ROGERS, Primary Examiner US. Cl. X.R. 88l; 96-66 

